P-434 - Evaluation of Novel Nematicide Treatment Protocols to Control Corky Ringspot Disease Vectored by Stubby Root Nematode Paratrichodorus allius on Potato
Associate Professor North Dakota State University Fargo, North Dakota, United States
Abstract Text: Many potato cultivars grown in North Dakota are susceptible to Corky Ringspot Disease, caused by Tobacco rattle virus and vectored by the stubby root nematode, Paratrichodorus allius. In 2024, 8 chemical treatment protocols, including Velum Rise, Velum Prime, Movento, a non-treated control and the industry standard Vydate, were applied to 25-row feet of ‘Yukon Gold’ potato through combinations of in-furrow bands, fungigation, and foliar spraying at various time points. Nematode genera were identified and quantified before application and at harvest. Tuber disease incidence and severity were quantified at harvest and at 90 days after harvest (DAH). At both time points, disease incidence ranged from 56%-82% for most treatments; but, incidence was significantly less (P< 0.05) at only 5% for treatments 2 and 4, which had in-furrow and foliar spray applications of Vydate at 45 and/or 60 days after planting. Similarly, disease severity at harvest ranged from 18%-31% for most treatments, but significantly less, at ~7.5%, for treatments 2 and 4. However, at 90DAH, disease severity rose to 10% for treatment 2 and 18% for treatment 4, making them statistically similar to other treatments. Initial population densities of stubby root nematode ranged from 0-900 per kg of soil in the field plots, with ~50% fewer nematodes at harvest, but there was no correlation between nematode densities and disease parameters. Yield ranged from 73 lbs for the non-treated control to 117 lbs for treatment 4, which is considered the best treatment protocol for highest yield and lowest disease pressure.
